I find it odd that there's no universal system for blocking calls from specific numbers. I'm guessing you could implement a spam filter, so Harassment/telemarketing wouldn't be a problem.
Right now you can often determine the address/owner of a telephone number, but that doesn't tell you who REALLY called because the VoIP company never passes on that info even to the telcos.
What we need is a law that forces VoIP providers (inc. Skype) to forward some real caller ID info onto the telcos, and then the telcos need to forward that info to the end user.
The insecurity of the caller ID system (i.e. it is trivially spoofed) is a legitimate problem however, since even if the VoIP provider did pass on the info, the scammer could override it.
Then we could blacklist VoIP providers that act as a haven for scammers, as we do with hosting providers that offer the same to email spammers.
Even without this, one could develop Bayesian filters to detect likely spam calls and run them through a captcha first.
Probably because of legacy issues
In the same way you don't know the internal IP of a connection to a webserver
Caller ID is sent by the initiating exchange, and it is not used for the backwards connection
See the ISDN specs for more details
[1] https://play.google.com/store/apps/details?id=com.mrnumber.b...
Edit: oh, API for use by another app. Gotcha.
I can register a personal number on a Do Not Call list, but there are exemptions for political parties, charities, religious organisations and market researchers. Market researchers and charities make a lot of calls.
There is no equivalent for business numbers.
And then on top of that, there are countless telemarketing calls from overseas. The latest frustration on my business number is outsourcing spammers calling to explain that they will be sending me (spam) email in a moment and telling me the title of the attachment, etc. So, spam plus an interrupting phone call - fantastic! Thanks subcontinent!
You might be able to have some fun with them at least - or just abuse the heck out of them (unfortunately telemarketers seem pretty blasee about it).
As for your private line, if you don't recognize the number just don't answer it? My cellphone blocks all calls during the night (with an exception for families) but I think it can block all numbers not in my contacts.
It's the pointless interruption I can't stand.
One of my colleagues absolutely swears by it.
I think what we need is an Adblock for phone numbers that categorizes all spammers, debt collectors, etc and blocks them instantly on everyone's phones.
TelAPI has such neat features.
Callcentric's whitelisting + call routing rules combined with a download of your android phonebook makes an effective whitelist filter. Anyone not in your address book is just sent to voicemail.
I have a contact "Blocked Telemarketers" for exactly this purpose. Every time a new one hits me, I just add its number to this contact. Trivially easy.
What I really want though is a very simple feature. I don't want my phone to accept phone calls unless the number is in my address book already. Its so straightforward and already implemented in other communication mediums, I do not understand why it is not a feature yet.
Just one vendor including this feature would force all of them to.
My parents do this the old fashioned way. They don't pickup unless they recognize the number.
In fact, my colleagues do the same, and this has actually caused problems for On call if the colleague calling at 4am isn't in the callee's circle of friends.
Tap and hold on the number in your call history, and "Block caller" is right there!
Unfortunately, the "and hold" bit is rather hard to figure out. (And I started out knowing it could be done, but not how.)
There are some serious discoverability problems with the latest wave of pretty interfaces.
I've got quite a long list of blocked sales numbers, mostly Virgin Media and Three.
One example is Xiaomi's MIUI [ http://en.miui.com/thread-118672-1-1.html ]: "MIUI Call Blocker - How to Block/Unblock Contacts ?"
It kind of points to the fact that long before the internet existed, we were bad at building systems that allowed victims of harassment to have any recourse against abusers.
It's really only POTS that doesn't have such functionality.
At least a couple of times a month for about a year, we'd get a fax call at around 2am. The phone company refused to do anything about it, saying that if it wasn't explicitly harassing, it was OK. That makes me not want to be their customer anymore.
So we switched to a VoIP service, which we can set up blacklists or whitelists for as we like. No more problems.
I think the underlying problem is that the TelCo just doesn't care: they're happy to lose you as a POTS customer. They lose money on residential service, so if they can go by the book for regulatory purposes and still shed those unprofitable customers, they're winning.